1. Field of the Invention
The present invention relates to systems and methods for determining a location relevant to a radio receiver or a location relevant to a user associated with a radio receiver.
2. Description of Related Art
Wireless telephones, pagers, marine radios, and Citizen's Band (CB) radios are examples of two-way communication systems that typically include a radio receiver and a radio transmitter for wireless communications. Radios, televisions, and radio scanners are examples of one-way communication systems that typically include a radio receiver for receiving wireless communications, but do not typically include a radio transmitter for transmitting wireless communications. For convenience, the term “communication system” is used to refer to systems capable of at least receiving wireless communications, including one-way communication systems and two-way communication systems.
In recent years, a number of service systems have been implemented or proposed which would provide a given service based on the location of a communication system. Such location-based service systems would provide a service in relation to a given location. For example, such a service could locate the nearest ATM, gas station, bank, police station, or restaurant, in relation to the location. The location can be determined using a global positioning satellite (GPS) system.
Another example of a prior location-based service relates specifically to radio scanners. Radio scanners, which are sometimes referred to as “police scanners,” typically include a frequency-scanning radio receiver that is programmable to monitor frequencies in a geographical area where the receiver is located. Various methods have been proposed for automating the programming process based on the location of the radio receiver. For example, U.S. Pat. Nos. 6,941,120 and 6,192,223 disclose methods for automatically programming radio scanners based on geographical location information that is received from a global positioning satellite (GPS) system.
While a GPS system can be used for determining the geographical location with accurate results, many communication systems are not capable of receiving and processing GPS data. In some cases, a user is required to purchase a GPS receiver separately in order to take advantage of features that rely on automatic detection of the geographical location of the communication system. Otherwise, manufacturers face increased expense in manufacturing or upgrading a communication system that it can receive and process GPS signals.
It would be desirable, therefore, to provide an improved method for determining a location.